Ryutaro Uchi

Amplification of PVT-1 is involved in poor prognosis via apoptosis inhibition in colorectal cancers

Background:We previously conducted gene expression microarray analyses to identify novel indicators for colorectal cancer (CRC) metastasis and prognosis from which we identified PVT-1 as a candidate gene. PVT-1, which encodes a long noncoding RNA, mapped to chromosome 8q24 whose copy-number amplification is one of the most frequent events in a wide variety of malignant diseases. However, PVT-1 molecular mechanism of action remains unclear.Methods:We conducted cell proliferation and invasion assays using colorectal cancer cell lines transfected with PVT-1siRNA or negative control siRNA. Gene expression microarray analyses on these cell lines were also carried out to investigate the molecular function of PVT-1. Further, we investigated the impact of PVT-1 expression on the prognosis of 164 colorectal cancer patients by qRT–PCR.Results:CRC cells transfected with PVT-1 siRNA exhibited significant loss of their proliferation and invasion capabilities. In these cells, the TGF-β signalling pathway and apoptotic signals were significantly activated. In addition, univariate and multivariate analysis revealed that PVT-1 expression level was an independent risk factor for overall survival of colorectal cancer patients.Conclusion:PVT-1, which maps to 8q24, generates antiapoptotic activity in CRC, and abnormal expression of PVT-1 was a prognostic indicator for CRC patients.

Exosomal microRNA in serum is a novel biomarker of recurrence in human colorectal cancer.

Background:Functional microRNAs (miRNAs) in exosomes have been recognised as potential stable biomarkers in cancers. The aim of this study is to identify specific miRNAs in exosome as serum biomarkers for the early detection of recurrence in human colorectal cancer (CRC).Methods:Serum samples were sequentially obtained from six patients with and without recurrent CRC. The miRNAs were purified from exosomes, and miRNA microarray analysis was performed. The miRNA expression profiles and copy number aberrations were explored using microarray and array CGH analyses in 124 CRC tissues. Then, we validated exosomal miRNAs in 2 serum sample sets (90 and 209 CRC patients) by quantitative real-time RT–PCR.Results:Exosomal miR-17-92a cluster expression level in serum was correlated with the recurrence of CRC. Exosomal miR-19a expression levels in serum were significantly increased in patients with CRC as compared with healthy individuals with gene amplification. The CRC patients with high exosomal miR-19a expression showed poorer prognoses than the low expression group (P<0.001).Conclusions:Abundant expression of exosomal miR-19a in serum was identified as a prognostic biomarker for recurrence in CRC patients.

Identification of a bona fide microRNA biomarker in serum exosomes that predicts hepatocellular carcinoma recurrence after liver transplantation

BackgroundPredictive biomarkers for the recurrence of hepatocellular carcinoma (HCC) have great benefit in the selection of treatment options, including liver transplantation (LT), for HCC. The purpose of this study was to identify specific microRNAs (miRs) in exosomes from the serum of patients with recurrent HCC and to validate these molecules as novel biomarkers for HCC recurrence.MethodsWe employed microarray-based expression profiling of miRs derived from exosomes in the serum of HCC patients to identify a biomarker that distinguishes between patients with and without HCC recurrence after LT. This was followed by the validation in a separate cohort of 59 HCC patients who underwent living related LT. The functions and potential gene targets of the recurrence-specific miRs were analysed using a database, clinical samples and HCC cell lines.ResultsWe found that miR-718 showed significantly different expression in the serum exosomes of HCC cases with recurrence after LT compared with those without recurrence. Decreased expression of miR-718 was associated with HCC tumour aggressiveness in the validated cohort series. We identified HOXB8 as a potential target gene of miR-718, and its upregulation was associated with poor prognosis.ConclusionCirculating miRs in serum exosomes have potential as novel biomarkers for predicting HCC recurrence.

Integrated Multiregional Analysis Proposing a New Model of Colorectal Cancer Evolution.

Understanding intratumor heterogeneity is clinically important because it could cause therapeutic failure by fostering evolutionary adaptation. To this end, we profiled the genome and epigenome in multiple regions within each of nine colorectal tumors. Extensive intertumor heterogeneity is observed, from which we inferred the evolutionary history of the tumors. First, clonally shared alterations appeared, in which C>T transitions at CpG site and CpG island hypermethylation were relatively enriched. Correlation between mutation counts and patients’ ages suggests that the early-acquired alterations resulted from aging. In the late phase, a parental clone was branched into numerous subclones. Known driver alterations were observed frequently in the early-acquired alterations, but rarely in the late-acquired alterations. Consistently, our computational simulation of the branching evolution suggests that extensive intratumor heterogeneity could be generated by neutral evolution. Collectively, we propose a new model of colorectal cancer evolution, which is useful for understanding and confronting this heterogeneous disease.

Up-regulation of NEK2 by microRNA-128 methylation is associated with poor prognosis in colorectal cancer.

BackgroundNIMA-related kinase 2 (NEK2), an enzyme involved in the development and progression of cancer, is abnormally expressed in a wide variety of human cancers, including colorectal cancer (CRC), and is known to have roles in cell division and mitotic regulation through centrosome splitting. We investigated the clinical significance of NEK2 in CRC. In particular, we examined miR-128 expression, which is thought to target NEK2.MethodsWe measured NEK2 mRNA and miR-128 levels in clinical samples by quantitative reverse transcription real-time PCR and analyzed the associations between NEK2 levels, miR-128 levels, clinicopathological factors, and prognoses. Furthermore, we performed in vitro assays using a pre-miR-128 precursor and conducted miR-128 methylation analyses.ResultsMiR-128 inhibited NEK2 expression and cancer cell proliferation via cell cycle arrest. Moreover, miR-128 was silenced by DNA methylation. Increased NEK2 expression was associated with serosal invasion, lymphatic invasion, and peritoneal dissemination. Patients with high NEK2 expression also had significantly poorer prognoses. Multivariate analysis indicated that high NEK2 expression was an independent prognostic factor for survival. Patients with high miR-128 expression had significantly lower NEK2 expression and lower recurrence rates than those with low miR-128 expression.ConclusionsNEK2 may be an independent prognostic factor for CRC and was regulated by miR-128, a microRNA that was subjected to epigenetic regulation. Thus, this miR-128/NEK2 pathway may be a prospective therapeutic target for patients with CRC.

Paired related homoeobox 1, a new EMT inducer, is involved in metastasis and poor prognosis in colorectal cancer

Background:Paired related homoeobox 1 (PRRX1) has been identified as a new epithelial-mesenchymal transition (EMT) inducer in breast cancer. However, the function of PRRX1 in colorectal cancer (CRC) has not been elucidated.Methods:We utilised ectopic PRRX1-expressing cell lines to analyse the function of PRRX1 in CRC. The clinical significance of PRRX1 was also examined on three independent CRC case sets.Results:PRRX1 induced EMT and the stem-like phenotype in CRC cells. In contrast to studies of breast cancer, abundant expression of PRRX1 was significantly associated with metastasis and poor prognosis in CRC.Conclusion:PRRX1 is an indicator of metastasis and poor prognosis in CRC cases. Further investigation is required to uncover the signalling network regulating PRRX1.

Rapid intraoperative visualization of breast lesions with γ-glutamyl hydroxymethyl rhodamine green

We previously developed γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG) as a tool to detect viable cancer cells, based on the fact that the enzyme γ-glutamyltranspeptidase (GGT) is overexpressed on membranes of various cancer cells, but is not expressed in normal tissue. Cleavage of the probe by GGT generates green fluorescence. Here, we examined the feasibility of clinical application of gGlu-HMRG during breast-conserving surgery. We found that fluorescence derived from cleavage of gGlu-HMRG allowed easy discrimination of breast tumors, even those smaller than 1 mm in size, from normal mammary gland tissues, with 92% sensitivity and 94% specificity, within only 5 min after application. We believe this rapid, low-cost method represents a breakthrough in intraoperative margin assessment during breast-conserving surgery.

Decreased Expression of Fructose-1,6-bisphosphatase Associates with Glucose Metabolism and Tumor Progression in Hepatocellular Carcinoma

Fructose-1,6-bisphosphatase (FBP1), the rate-limiting enzyme in gluconeogenesis, is reduced in expression in certain cancers where it has been hypothesized to act as a tumor suppressor, including in hepatocellular carcinoma (HCC). Here, we report functional evidence supporting this hypothesis, providing a preclinical rationale to develop FBP1 as a therapeutic target for HCC treatment. Three independent cohorts totaling 594 cases of HCC were analyzed to address clinical significance. Lower FBP1 expression associated with advanced tumor stage, poor overall survival, and higher tumor recurrence rates. In HCC cell lines, where endogenous FBP1 expression is low, engineering its ectopic overexpression inhibited tumor growth and intracellular glucose uptake by reducing aerobic glycolysis. In patient specimens, promoter methylation and copy-number loss of FBP1 were independently associated with decreased FBP1 expression. Similarly, FBP1 downregulation in HCC cell lines was also associated with copy-number loss. HCC specimens exhibiting low expression of FBP1 had a highly malignant phenotype, including large tumor size, poor differentiation, impaired gluconeogenesis, and enhanced aerobic glycolysis. The effects of FBP1 expression on prognosis and glucose metabolism were confirmed by gene set enrichment analysis. Overall, our findings established that FBP1 downregulation in HCC contributed to tumor progression and poor prognosis by altering glucose metabolism, and they rationalize further study of FBP1 as a prognostic biomarker and therapeutic target in HCC patients. Cancer Res; 76(11); 3265-76. ©2016 AACR.

CHD8 is an independent prognostic indicator that regulates Wnt/β-catenin signaling and the cell cycle in gastric cancer

The chromodomain helicase DNA-binding (CHD) family comprises a class of chromatin remodeling enzymes. Previous studies suggest that CHD8 may negatively regulate various genes and signaling pathways, such as the Wnt/β‑catenin pathway. However, few studies have investigated the role of CHD8 in cancer cells. We analyzed the expression of CHD8 in cancer lesions and corresponding non-cancerous tissues to demonstrate the prognostic significance of CHD8 expression in 101 cases of gastric cancer. We also investigated the functional implications of aberrant CHD8 expression by conducting gene set enrichment analysis (GSEA). Expression of CHD8 mRNA was significantly lower in gastric cancer tissues compared to that in corresponding normal tissues (P=0.003). In multivariate analysis for overall survival, we found that CHD8 expression was an independent prognostic factor in gastric cancer. Moreover, GSEA revealed that CHD8 was significantly associated with genes involved in the Wnt/β‑catenin pathway and in the cell cycle. In addition, knockdown of CHD8 expression in the gastric cancer cell lines, MKN45 and NUGC4, promoted proliferation. In conclusion, the present study suggests that loss of CHD8 expression may be a novel indicator for biological aggressiveness in gastric cancer.

The AURKA/TPX2 axis drives colon tumorigenesis cooperatively with MYC

BACKGROUND The MYC oncogene has long been established as a central driver in many types of human cancers including colorectal cancer. However, the realization of MYC-targeting therapies remains elusive; as a result, synthetic lethal therapeutic approaches are alternatively being explored. A synthetic lethal therapeutic approach aims to kill MYC-driven tumors by targeting a certain co-regulator on the MYC pathway. PATIENTS AND METHODS We analyzed copy number and expression profiles from 130 colorectal cancer tumors together with publicly available datasets to identify co-regulators on the MYC pathway. Candidates were functionally tested by in vitro assays using colorectal cancer and normal fibroblast cell lines. Additionally, survival analyses were carried out on another 159 colorectal cancer patients and public datasets. RESULTS Our in silico screening identified two MYC co-regulator candidates, AURKA and TPX2, which are interacting mitotic regulators located on chromosome 20q. We found the two candidates showed frequent co-amplification with the MYC locus while expression levels of MYC and the two genes were positively correlated with those of MYC downstream target genes across multiple cancer types. In vitro, the aberrant expression of MYC, AURKA and TPX2 resulted in more aggressive anchorage-independent growth in normal fibroblast cells. Furthermore, knockdown of AURKA or TPX2, or treatment with an AURKA-specific inhibitor effectively suppressed the proliferation of MYC-expressing colorectal cancer cells. Additionally, combined high expression of MYC, AURKA and TPX2 proved to be a poor prognostic indicator of colorectal cancer patient survival. CONCLUSIONS Through bioinformatic analyses and experiments, we proposed TPX2 and AURKA as novel co-regulators on the MYC pathway. Inhibiting the AURKA/TPX2 axis would be a novel synthetic lethal therapeutic approach for MYC-driven cancers.